Alfin Catalysts and the Polymerization of Butadiene

1951 ◽  
Vol 24 (1) ◽  
pp. 35-53
Author(s):  
Avery A. Morton
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Catalytic Polymerization ◽  
Sodium Salts ◽  
Multiple Reactions ◽  
Secondary Reactions ◽  
History Of ◽  
Organosodium Compounds

Abstract Alfin catalysts are special combinations of sodium salts which cause the rapid catalytic polymerization of butadiene to polymers of unusually high molecular weight. These polymerizations show characteristics which are common to all reactions of organosodium compounds, namely, the tendency to undergo multiple reactions. The reagents are also insoluble aggregates of ions whose behavior is affected by the ions in the aggregate. The history of the discovery is reviewed. The catalytic polymerization shows no property in common with the conventional sodium process for polymerizing butadiene. The present problems center in the elimination of secondary reactions that are known to occur. The theory by which all the reactions occur, including polymerizations induced by organosodium compounds, is discussed. Progress toward the practical use of the alfin polymers is being made.

scholarly journals High Molecular Weight Fibrinogen Complexes in Patients with History of Myocardial Infarction and Cerebrovascular Disorders

1977 ◽  
Author(s):  
G.G. Neri Serneri ◽  
G.F. Gensini ◽  
R. Abbate ◽  
D. Prisco ◽  
C. Mugnaini ◽  
...  
Keyword(s):  
Myocardial Infarction ◽  
Molecular Weight ◽  
High Molecular Weight ◽  
Cerebrovascular Disorders ◽  
Gel Filtration ◽  
Globular Proteins ◽  
Void Volume ◽  
Beta Alanine ◽  
Cross Linkage ◽  
History Of

The increased turnover of fibrinogen and decreased platelet survival observed in many patients with history of myocardial infarction (MIP) and in patients with chronic cerebrovascular disorders (CVP) (Neri Serneri et al 1970, Harker and Slichter 1972) could suggest a hypercoagulable state. We investigated 28 MIP, 23 CVP and 31 controls for circulating high molecular weight fibrinogen complexes (HMWFC) by gel-filtration (agarose 4%, 100–200 m, column 1.5 × 90 cm, buffer Tris-Cl-citrate pH 7.6, flow 13 ml/hour, recording of OD at 280 um) of plasma beta-alanine precipitate. HMWFC are eluted in a peak at an alution volume corresponding to the void volume of the column, at which volume globular proteins of MW over 1 million are eluted. HMWFC concentration was in the controls 2.98±1.52% of the fibrinogen eluted, in MIP 8.27±2.9 % (P<0.0l) and in CVP 7.48±1.9 % (P<0.01). When HMWFC concentration was higher than 6-7%, PAA electrophoresis of the eluted complexes (after mercaptoethanol reduction) allowed to detect gamma-gamma dimers, so indicating the cross-linkage of HMWFC. Heparin treatment (12,500 U × 2) markedly lowered the concentration of HMWFC and made gamma-gamma dimers undetectable. These results indicate that in MIP and in CVP a hypercoagulability frequently exists.

Titanium amidate complexes as active catalysts for the synthesis of high molecular weight polyethylene

2015 ◽  
Vol 93 (7) ◽  
pp. 775-783 ◽  
Author(s):  
Patricia Horrillo-Martinez ◽  
David C. Leitch ◽  
Scott A. Ryken ◽  
Robert K. Thomson ◽  
J. David Beard ◽  
...  
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Ethylene Polymerization ◽  
Catalytic Polymerization ◽  
Binding Motifs ◽  
Co Catalyst ◽  
Multiple Binding ◽  
Polymeric Chains ◽  
Ultra High Molecular Weight

A series of titanium and zirconium bis(amidate) complexes of the type L2MX2, where L is an amidate ligand, and X is either –NMe2 or –Cl, were prepared in 60%–83% yield and fully characterized. Multiple binding motifs are observed as the amidate ligand can bind in κ1- and κ2-modes. These complexes were then subjected to screening the catalytic polymerization of ethylene. All catalysts, after reaction with suitable co-catalyst, were functional for ethylene polymerization, though not for the copolymerization of ethylene and longer linear 1-alkenes. Polyethylene was formed in the range of 1000–4000 kDa, and with PDI values as low as 1.3. These long polymeric chains are considered as ultra-high molecular weight polyethylene (UHMWPE).

Compartmentalized polymerization in aqueous and organic media to low-entangled ultra high molecular weight polyethylene

2021 ◽  
Author(s):  
Florian P. Wimmer ◽  
Viktoria Ebel ◽  
Felix Schmidt ◽  
Stefan Mecking
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Functional Group ◽  
Aqueous Media ◽  
Organic Media ◽  
Catalytic Polymerization ◽  
Ultra High Molecular Weight

Catalytic polymerization in compartmentalized aqueous or non-aqueous media, respectively, with functional-group tolerant Ni(ii) catalysts yields low-entangled UHMWPE.

Microtubule motors and other maps

1990 ◽  
Vol 48 (3) ◽  
pp. 1-1
Author(s):  
Richard B. Vallee
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Cytoplasmic Dynein ◽  
Organelle Transport ◽  
Structural Components ◽  
Microtubule Associated Proteins ◽  
Microtubule Motors ◽  
Associated Proteins ◽  
The Subject ◽  
Intracellular Motility

Microtubules are involved in a number of forms of intracellular motility, including mitosis and bidirectional organelle transport. Purified microtubules from brain and other sources contain tubulin and a diversity of microtubule associated proteins (MAPs). Some of the high molecular weight MAPs - MAP 1A, 1B, 2A, and 2B - are long, fibrous molecules that serve as structural components of the cytamatrix. Three MAPs have recently been identified that show microtubule activated ATPase activity and produce force in association with microtubules. These proteins - kinesin, cytoplasmic dynein, and dynamin - are referred to as cytoplasmic motors. The latter two will be the subject of this talk.Cytoplasmic dynein was first identified as one of the high molecular weight brain MAPs, MAP 1C. It was determined to be structurally equivalent to ciliary and flagellar dynein, and to produce force toward the minus ends of microtubules, opposite to kinesin.

Studies on the Functionality of Newly Synthesized Fibrinogen after Treatment of Acute Myocardial Infarction with Streptokinase, Increase in the Rate of Fibrinopeptide Release

1993 ◽  
Vol 70 (06) ◽  
pp. 0978-0983 ◽  
Author(s):  
Edelmiro Regano ◽  
Virtudes Vila ◽  
Justo Aznar ◽  
Victoria Lacueva ◽  
Vicenta Martinez ◽  
...  
Keyword(s):  
Myocardial Infarction ◽  
Acute Myocardial Infarction ◽  
Molecular Weight ◽  
Steady State ◽  
High Molecular Weight ◽  
Coronary Arteries ◽  
Risk Index ◽  
Weight Fraction ◽  
High Molecular Weight Fraction ◽  
Fibrinopeptide A

SummaryIn 15 patients with acute myocardial infarction who received 1,500,000 U of streptokinase, the gradual appearance of newly synthesized fibrinogen and the fibrinopeptide release during the first 35 h after SK treatment were evaluated. At 5 h the fibrinogen circulating in plasma was observed as the high molecular weight fraction (HMW-Fg). The concentration of HMW-Fg increased continuously, and at 20 h reached values higher than those obtained from normal plasma. HMW-Fg represented about 95% of the total fibrinogen during the first 35 h. The degree of phosphorylation of patient fibrinogen increased from 30% before treatment to 65% during the first 5 h, and then slowly declined to 50% at 35 h.The early rates of fibrinopeptide A (FPA) and phosphorylated fibrinopeptide A (FPAp) release are higher in patient fibrinogen than in isolated normal HMW-Fg and normal fibrinogen after thrombin addition. The early rate of fibrinopeptide B (FPB) release is the same for the three fibrinogen groups. However, the late rate of FPB release is higher in patient fibrinogen than in normal HMW-Fg and normal fibrinogen. Therefore, the newly synthesized fibrinogen clots faster than fibrinogen in the normal steady state.In two of the 15 patients who had occluded coronary arteries after SK treatment the HMW-Fg and FPAp levels increased as compared with the 13 patients who had patent coronary arteries.These results provide some support for the idea that an increased synthesis of fibrinogen in circulation may result in a procoagulant tendency. If this is so, the HMW-Fg and FPAp content may serve as a risk index for thrombosis.

The Effect of Dextran of Various Molecular Weight on the Coagulation in Dogs

1961 ◽  
Vol 06 (01) ◽  
pp. 015-024 ◽  
Author(s):  
Sven Erik Bergentz ◽  
Oddvar Eiken ◽  
Inga Marie Nilsson
Keyword(s):  
Molecular Weight ◽  
Body Weight ◽  
High Molecular Weight ◽  
Bleeding Time ◽  
Factor Vii ◽  
Low Molecular Weight ◽  
Factor V ◽  
Coagulation Mechanism ◽  
Coagulation Defects

Summary1. Infusions of low molecular weight dextran (Mw = 42 000) to dogs in doses of 1—1.5 g per kg body weight did not produce any significant changes in the coagulation mechanism.2. Infusions of high molecular weight dextran (Mw = 1 000 000) to dogs in doses of 1—1.5 g per kg body weight produced severe defects in the coagulation mechanism, namely prolongation of bleeding time and coagulation time, thrombocytopenia, pathological prothrombin consumption, decrease of fibrinogen, prothrombin and factor VII, factor V and AHG.3. Heparin treatment of the dogs was found to prevent the decrease of fibrinogen, prothrombin and factor VII, and factor V otherwise occurring after injection of high molecular weight dextran. Thrombocytopenia was not prevented.4. In in vitro experiments an interaction between fibrinogen and dextran of high and low molecular weight was found to take place in systems comprising pure fibrinogen. No such interaction occurred in the presence of plasma.5. It is concluded that the coagulation defects induced by infusions of high molecular weight dextran are due to intravascular coagulation.

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